Devices for driving posts into the ground are well known. Traditionally, most of those devices have been of the type wherein a relatively large dead mass is raised a substantial distance above the post to be driven and then released. Under the influence of gravity the mass falls until it hits the uppermost end of the post, driving the opposite end into the ground.
Generally, post drivers must be suitable for mounting on moveable platforms, such as a truck chassis, in order to permit movement of the post driver from one location to the next. Because of the necessity for making the device mobile, the traditional gravity devices described above have certain disadvantages. The mass of the dead weight which does the driving must be fairly large to accomplish the purpose; yet, the larger it becomes the more difficultly there is in making it mobile. Moreover, because the energy imparted to the post by the weight is directly proportional to the height that the weight is raised above the post prior to release, a balance must be struck between the height of the boom most desirable for use in driving posts and the height most suitable for maintaining mobility of the device.
Additionally, the process of raising a weight and permitting it to fall onto a post is a rather slow and tedious procedure. With labor costs increasing rapidly, the time required to drive posts by the traditional method represents a substantial shortcoming.
Thus, it is desirable to have a post driver device which does not require an excessively long boom, does not require a very large moveable dead mass and drives posts quite rapidly.